Abstract

Native to Australasia, Eucalyptus (sensu lato) is one of the most planted genera of trees in the world. However, the sustainability of Eucalyptus species as plantation trees in non-native areas is increasingly threatened by the introduction and spread of Eucalyptus-feeding insects from Australia. We examine patterns and potential trends with respect to the global spread of Eucalyptus-feeding insects. Likely pathways of introduction and drivers of the rapid distribution of these insects, as well as management options are considered. The rate of introductions is shown to have increased nearly fivefold since the 1980s. As a result, the number of non-native pests of eucalypts outside of Australia has doubled in less than three decades. Furthermore, the rate of secondary spread among continents has also increased. Surprisingly, we found no association between area planted and the number of pests or new introductions. Only a small number of countries have been the points of first detection outside the native range; these countries have acted as bridgeheads to other regions. Quarantine regulations aimed at reducing the spread of invasive organisms appear to be ineffective at a global scale, and pathways allowing these invasions to occur are poorly understood or unknown. An expanded suite of management options are needed to provide resilience against the rapid accrual and homogenization of eucalypt pests, thereby ensuring the sustainability of eucalypt forestry worldwide.

Notes

Acknowledgments

Members of the Tree Protection Cooperative Programme (TPCP), the National Research Foundation (NRF) and the Department of Trade and Industry (DTI) of South Africa, are acknowledged for their financial support. This paper had its origin at a workshop on “Drivers, impacts, mechanisms and adaptation in insect invasions” hosted by the DST-NRF Centre of Excellence for Invasion Biology in Stellenbosch, South Africa, in November 2014. Additional financial support was provided by HortGro, the National Research Foundation of South Africa (Grant 85417), Stellenbosch University, and SubTrop.

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